This invention claims priority of a German filed patent application DE 199 49 008.2.
The invention concerns an apparatus for loading substrates of various sizes into substrate holders.
The invention furthermore concerns a method for loading substrates of various sizes into a substrate holder provided therefor.
In critical-distance (CD) measurement systems that are set up for transmitted-light measurements, the substrates are transported in frames. In this context the masks are usually introduced into the frames by hand and outside the measurement system. The frames with the introduced substrates are then directly loaded onto and unloaded from the measurement stage (X-Y carriage). This is not practical for use in the production environment of semiconductor manufacturers. The substrate handling system used in the Leica(copyright) LMS IPRO of Leica Microsystems Wetzlar GmbH is automated, but is not designed for large substrates or for different substrate holders.
It is therefore the object of the invention to create an apparatus which makes possible reliable introduction of various substrates into a measuring instrument. Reliable transfer of the substrates into the measuring instrument is of particular importance in this context. In addition, it is intended by way of the apparatus to prevent damage to the substrates due to mishandling of the substrate holders.
This object is achieved according to the present invention, in an apparatus of the kind cited initially, in that a base plate with peripheral rim is provided. Arranged on the base plate are at least three support means, each of which has configured on it different support surfaces for the various substrates. The support surfaces are arranged in stepped fashion on the support means. Receiving elements, which support the transport frame in such a way that it surrounds the support means and is aligned in terms of its position, are provided for the substrate holders.
A further object of the invention is to create a method which makes possible the delivery of various substrates into a measuring instrument. An additional object is to guarantee reliable and damage-free handling of the various substrates.
This object is achieved according to the present invention, in a method of the kind cited initially, in that the method comprises the following steps:
determining the type of substrate holder;
depositing the substrate holder onto the support means provided on a
base plate of the apparatus;
placing a substrate onto support means provided therefor;
determining the size of the substrate;
checking conformity between the substrate holder and substrate; and
transferring the substrate into the substrate holder provided for the substrate.
Advantageous developments are evident from the features of the dependent claims.
With the configuration according to the present invention of a loading station for introducing the various substrates into a substrate holder, it becomes possible to accomplish reliable or automated handling of the individual substrates. In addition, placement of the substrates in the substrate holders means that the substrates arrive already aligned and thus in a defined position. The advantage of this is that defined conditions can be assumed when measuring the substrates. The substrates are transferred into the measuring instrument together with the substrate holders. This offers the advantage that the substrate itself does not need to be introduced by hand by an operator into the measuring instrument. This prevents temperature gradients in the substrate that might result by being manually grasped.